There should be a machined flat that the distributor base clamps to. On that flat aft of the distributor should be where the serial numbers are stamped. Usually this takes some work to uncover. First a scraper and solvent to clean off the gunk, then a wire brush to remove the paint, which fills the stamping.
For the casting number and date code, look above the starter on the side of the block. Sometimes the number is behind the starter.
I don't remember what the 48 stands for, but I don't think it can be used to identify the engine.
